HOW IT WORKS?
Machines (Anti-Mosquito or mosquito repellent with mosquito sound) that emit ultrasonic sounds produce noises so high-pitched that they are undetectable to the human ear. This application provides that sound and do several things to repel insects. First, the sound that mimic predators, which scare away insects. A mosquito, for example, may think a predatory dragonfly is nearby. Moths may believe a bat is swooping down to feed. This is also a sonic sound (ultra sound).
You can find more info in this anti mosquito applicaton’s info section.